I was on B&H's website and suddenly had a question that applies to both fast and slow lenses. Why does Nikon make so many different zoom's? For example, I can get a single zoom lens that covers 18-200mm for about $650. Now (and I'm just throwing numbers in here, but you get the idea) Nikon also makes a 18-50, a 70-135, and a 135-210. Why would I want to mess around with not only the added expense of multiple lenses, but also changing them? I could understand it if lens that covers the broader focal length was a slow lens and the ones that cover a smaller spectrum were faster, but they aren't. They do this with lenses that cover the 4.5-5.6 and the ones that are in the 2.8 range. :study:

I was on B&H's website and suddenly had a question that applies to both fast and slow lenses. Why does Nikon make so many different zoom's? For example, I can get a single zoom lens that covers 18-200mm for about $650. Now (and I'm just throwing numbers in here, but you get the idea) Nikon also makes a 18-50, a 70-135, and a 135-210. Why would I want to mess around with not only the added expense of multiple lenses, but also changing them? I could understand it if lens that covers the broader focal length was a slow lens and the ones that cover a smaller spectrum were faster, but they aren't. They do this with lenses that cover the 4.5-5.6 and the ones that are in the 2.8 range. :study:

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Suppose, for example, you had no interest in focal lengths beyond 50mm, why pay for an 18-200. Instead, purchase only what you need, the 18-50.

Not all lenses are of the same quality. In order to make a lens which covers such a vast focal length range (ie 18-200) some sacrifices in lens design and resulting quality are made. I myself use prime lenses whenever possible, which only cover one focal length, as in 50mm, or 85mm. I switch them often. Why? They are the simplest lens designs and they offer very wide max apertures and superior image quality.

I have a Canon camera and alot of people suggested to me that i should use Sigma lenses, because they are cheap... i would rather use canon lenses where a canon lens of lets say 24 - 70mm costs the same as lets say a sigma 20-300mm lens (these are just random numbers). The main difference usually is the f stop of the lenses are not constant and also i read alot of people say that the image quality of the lense that has the 20-300mm (for example) is lower that the lenses that has for example 200-300mm zoom.

Not all lenses are of the same quality. In order to make a lens which covers such a vast focal length range (ie 18-200) some sacrifices in lens design and resulting quality are made. I myself use prime lenses whenever possible, which only cover one focal length, as in 50mm, or 85mm. I switch them often. Why? They are the simplest lens designs and they offer very wide max apertures and superior image quality.

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Agree. I also prefer primes when warranted by the circumstances. My favorites are 50mm f/1.4 and 85mm f/1.8. I also own Nikon's 18-200VR and it's great as a "walk around" lens. There are occasions when versatility concerns dominate quality concerns.

I was on B&H's website and suddenly had a question that applies to both fast and slow lenses. Why does Nikon make so many different zoom's? For example, I can get a single zoom lens that covers 18-200mm for about $650. Now (and I'm just throwing numbers in here, but you get the idea) Nikon also makes a 18-50, a 70-135, and a 135-210. Why would I want to mess around with not only the added expense of multiple lenses, but also changing them? I could understand it if lens that covers the broader focal length was a slow lens and the ones that cover a smaller spectrum were faster, but they aren't. They do this with lenses that cover the 4.5-5.6 and the ones that are in the 2.8 range. :study:

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Why don't we all drive a Prius? Why does Toyota make more models than the Prius? Same thing when it comes to lenses. They all are designed to do the same function, but the quality that they produce are quite different.

"Super zoom" 18-200mm 11.1x zoom range lenses give you a huge range at the expense of image quality. The cheap $100 18-55 kit lens is optically superior to the 18-200mm lens from 18-55, as is the cheap $170 55-200mm telephoto zoom lens from 55-200mm. The 18-200 gives you a lot of convenience of not having to switch lenses, but not the best quality. Primes are the exact opposite. The cheap $100 50mm f/1.8 lens is optically superior to just about anything Nikon makes at 50mm because it only has to cover one focal length, and does so nearly perfectly. It also gives you a lot of speed. The $1200 professional 17-55mm f/2.8 zoom lens is not any better at 50mm than the $100 prime is, and is a stop slower to boot. The 17-55 gives you the ability to get top notch quality like the prime, but also zooms at the same time.